The present invention relates to a focus control device, an endoscope apparatus, a focus control method, and the like.
An improvement in detection accuracy of a lesion in a body cavity has been desired in the field of endoscopic diagnosis. An endoscope that includes a magnifying optical system that improves the detection accuracy by magnifying the difference in tissue between a lesion area and a normal area at a magnification almost equal to that of a microscope (hereinafter may be appropriately referred to as “magnifying endoscope”) has been known.
A magnifying endoscope may achieve a magnification of several ten to several hundred times. The microstructure of a mucous membrane surface layer and a blood vessel distribution pattern can be observed by utilizing such a magnifying endoscope in combination with a stain solution or a blood vessel-enhanced (weighted) image (NBI image) obtained using narrow-band illumination light. It is known that a lesion area and a normal area differ in the above pattern, and the above pattern has been used as a criterion of lesion diagnosis.
JP-A-2-304413 discloses an endoscope that implements an autofocus control process, and allows the user to start or stop the autofocus process using a switch provided in an operation section of the endoscope.